1. Field of the Invention
The present invention relates to a centrifugal compressor which can be adapted to compress gas, such as a gaseous coolant in a refrigeration cycle.
2. Description of the Related Art
There are mainly three kinds of compressors, i.e. centrifugal compressor, reciprocating compressor and rotary compressor. Among these compressors, a centrifugal compressor to which the subject of the present invention is directed has a basic arrangement in which rotary compressor blades are accommodated in a stationary casing with diffusers on its periphery. The gas to be compressed in introduced into the casing through a central portion of the compressor blades and the compressed gas is discharged from the peripheral portion of the casing connected to the diffusers. In this known arrangement of the centrifugal compressor, there are fatal drawbacks in which a large friction occurs in a sealing mechanism of the compressor, and the compression efficiency substantially depends on the manufacturing precision of components of the compressor, particularly on an accuracy of a gap between the casing and the compressor blades. The inaccuracy results in a large mechanical loss, a large sealing loss and a large friction loss.
The primary object of the present invention is to eliminate the above mentioned drawbacks of the prior art by providing a new centrifugal compressor having a large compression ratio with a small capacity.